1. Field of the Invention
This invention relates to a screen unit and a display system in an image projection display.
2. Description of the Related Art
Hitherto, a projected image from a video projector has been projected onto a screen unit and has been reflected or transmitted, whereby the observer has viewed the image. In the screen unit, the semipermeable screen sheet itself has predetermined reflectivity and transmissivity. The semipermeable screen is thin and has no mechanical strength. Thus, the semipermeable screen has been bonded fully onto a transparent reinforcing sheet and has been covered in surroundings with a frame for use. Thus, it has been intricate to adjust the video projector to match the image and the frame of the screen unit.
In the screen unit in the related art as described above, the screen sheet providing the image projection face is easily bent because of the thermal expansion coefficient difference between the screen sheet and the reinforcing transparent sheet. Since the frame touches the screen sheet, adjustment for matching the image with the frame is intricate. Further, in the display system in the related art as described above, when the observer facing one display face of the screen unit simultaneously displaying a reflected image and a transmitted image goes round to the back, the front and the back of the image are reversed; this is a problem.